A firefighter having at least 7 years of creditable service who becomes disabled as a result of any cause other than an act of duty, and who is found, pursuant to Section 4-112, to be physically or mentally permanently disabled so as to render necessary his or her being placed on disability pension, shall be granted a disability pension of 50% of the monthly salary attached to the rank held by the firefighter in the fire service at the date he or she is removed from the municipality’s fire department payroll. If a firefighter dies while still disabled and receiving a disability pension under this Section, the disability pension shall continue to be paid to the firefighter’s survivors in the sequence provided in Section 4-114 if that disability pension is greater than the survivors pension provided under subsection (a) of Section 4-114.